ES2263679T3 - PREPARATION PROCEDURE OF A DILITIATED INDICATOR. - Google Patents

Abstract

The present invention relates to a process for the preparation of a dilithiated initiator usable in anionic polymerization, a process for the preparation by anionic polymerization of a living diene elastomer which is provided with a carbon-lithium group at each of its chain ends, and a process for the preparation of a copolymer having three blocks starting from said living diene elastomer. The process for the preparation of a dilithiated initiator according to the invention involves of reacting a first reagent, a dialkenyl benzene, and a second reagent, secondary butyllithium, in the presence of a diamine, in an aliphatic or alicyclic hydrocarbon solvent, such that the ratio of the number of moles of first reagent to the number of moles of second reagent is substantially equal to 0.5, so that the initiator obtained is essentially a bi-adduct resulting from the addition of a molecule of secondary butyllithium to each of the two double bonds in the dialkenyl benzene.

Description

Preparation procedure of an initiator diluted

The present invention relates to a preparation procedure of a diluted initiator usable in anionic polymerization, to a preparation process by anionic polymerization of a living dienic elastomer that has a carbon-lithium group at each end chain, and to a process for preparing a copolymer of three blocks from said living elastomer dienic.

The preparation of polymerization initiators Diluted has been described abundantly in the literature. The main difficulty that arises when this is done preparation is to get effectively dysfunctional initiators, it is say, that they are such that they allow the equirreactivity of the sites lithium carbon when the reactions of anionic polymerization launch these initiators.

The two ways of preparing such Most studied diluted initiators to date are:

- the coupling of radical anions.

For example, the preparation of 1,4-dilithiotetraphenylbutane can be cited, from a precursor consisting of 1,1-diphenylethylene (LJ Fetters et M. Morton, Macromolecules 2 , 453, 1969).

The main drawback of this first mode of preparation lies in the need to use lithium in state metallic, which represents a difficulty when doing the extrapolation on an industrial scale. In addition, the precursor used It has a very high cost; Y

- the addition of monolithic compounds on a diunsaturated compound.

Mention may be made, for example, of unsaturated compounds, those compounds bearing two diphenylethylene moieties, such as 1,3 bis (1-phenyletenyl) benzene (LH Tung et GYS Lo, Macromolecules 27 , 1680, 1994).

In this regard, the patent document International WO-A-89/04843 discloses a procedure for preparing a dilute initiator consisting of reacting, in cyclohexane, butyllithium secondary with 1,3-bis (1-phenyletenyl) benzene in stoichiometric quantities. To do it so that the well prepared initiator present a dysfunctional character in the At the time of polymerization, it should be noted that you must enter subsequently a polyamide in a polymerization medium.

A main drawback of this second mode of preparation lies in the lack of availability of precursors for an industrial scale exploitation.

The use of aromatic type precursors unsaturated (such as divinylbenzene, or even the 1,3-diisopropenylbenzene) allows to alleviate this inconvenient.

Thus, the reaction between the 1,3-diisopropenylbenzene and secondary butyl lithium It has been studied extensively. Two examples of setting can be cited in progress of this reaction:

- according to a first example, RP FOSS et al . (RP Foss et al ., Macromolecules 10 , 287, 1977) have particularly proposed an initiator obtained in the presence of 1,3-diisopropenylbenzene, secondary butyllithium and 0.1 equivalent lithium triethylamine. This initiator is obtained in the form of oligoisoprene, α, w-dilute, in order to solubilize it in a non-polar medium. Said initiator has been used for the preparation of polymers obtained by anionic route, and the effectively dysfunctional behavior of this initiator on the basis of the average molecular masses in
number and of the monomodal distributions of the molecular masses that have been obtained for these polymers.

However, as it appears in the document published by G. Gordon Cameron et G.M. Buchan (Polymer 20, 1129, 1979) after this document by R.P. Foss, you are molecular mass and mass distribution findings molecular testify only an average functionality for both carbon-lithium initiator sites, and these macrostructure elements do not constitute a sufficient condition to define the equirreactivity of these sites when done polymerization, that is, the effective functionality of the initiator.

Indeed, the single mode character mentioned for the molecular mass distributions can be explained considering the hypothesis that polymerization kinetics of each of the initiator species present (for example, residual monolithic compound, dilute compound, compounds polyilites provided with oligomerization of the 1,3-dusopropenylbenzene) are compensated.

- According to a second start-up example of the reaction between 1,3-diisopropenylbenzene and the secondary butyllitio, the American patent document US-A-5 464 914 also discloses the adding 10 equivalent lithium triethylamine to obtain of a dilitiated initiator. To do it so that the initiator so prepared present a dysfunctional character at the time of polymerization, it should be noted that you must enter subsequently a polyamide in the polymerization medium.

Ph TEYSSIE et al . they have recently completed the preparation of an initiator diluted by reaction of 1,3-diisopropenylbenzene with the thirdbutyl lithium, in stoichiometric amounts and in the presence of 1 equivalent lithium of triethylamine and at -20 ° C (Ph. Teyssie et al ., Macromolecules 29 , 2738 , 1996), in such a way that 1,3-diisopropenylbenzene is added dropwise over a third-butyl lithium / triethylamine solution.

This utilization of the third butyl lithium instead of the secondary butyllithium is expected to eliminate an inconvenience inherent in the use of secondary butyllithium, which resides in the production of oligomers in significant quantity. In effect, the third butyl lithium is more reactive than secondary butyl lithium, with which is preferably oriented the reaction of 1,3-diisopropenylbenzene with the third butyl lithium towards an addition of the lithiated compound on each of the two unsaturations carried by diisopropenylbenzene.

The exclusion chromatography technique by size (technique "SEC") has allowed to establish the absence of 1,3-disopropenylbenzene oligomers, and the technique of NMR 7 Li has shown the substantially total consumption of third butyl lithium

It will also be noted that the molecule , 3-diisopropenylbenzene / third butyl lithium as well obtained does not behave as a dysfunctional initiator at the moment of polymerization (site equirreactivity lithium carbon), rather than with the condition of adding a sufficient amount of a polar compound (tetrahydrofuran, for example).

International Patent Document WO-A-00/22004 discloses a process for preparing a dilute initiator consisting of reacting the diisopropenylbenzene with diethylether, then adding the mixture thus obtained to a secondary or tertiary alkyl lithium. The reaction of said mixture with a secondary alkyl lithium is carried out at a temperature.
ture between 40 ° C and 50 ° C or, with a tertiary alkylthio, at a temperature between 25 ° C and 50 ° C.

The applicant has discovered surprising that if it reacts, in a solvent aliphatic or alicyclic hydrocarbonate, a first reagent formed by a dialkenyl benzene and a second reagent formed by secondary butyllithium so that the proportion of the number of moles of the first reagent over the number of moles of the second reagent is substantially equal to 0.5, specifically in the presence of a diamine, an essentially dilute initiator is thus obtained constituted by a bi-adduct resulting from the addition of a secondary butyl lithium molecule on each of the two double bonds carried by dialkenylbenzene, being said effectively dysfunctional initiator, in the sense that carbon-lithium sites with which it is provided, are Equalreactive when an anonymous polymerization occurs later.

A title of aliphatic hydrocarbonate solvent Cyclohexane is used, for example.

Regarding said first reagent, it is used preferably by way of dialkenyl benzene the 1,3-diisopropenylbenzene.

Regarding said second reagent, it will be noted that an essential advantage of the present invention is that of using specifically the secondary butyllithium which is a less compound onerous than the third butyl lithium and that lends itself therefore better to an extrapolation on an industrial scale.

Regarding the diamines which, according to the invention, should be used to obtain such initiator, it can be cite, preferably, the diamines belonging to the group formed by tetramethylethylenediamine and tetraethylethylenediamine. These two preferred diamines are both two chelating agents. multidentado that are characterized by a chemical structure and a analogous activity

According to another characteristic of the invention, add the first reagent at once to the second reagent, then the diamine is introduced on a reactive mixture that understand these reagents.

It will be noted that such addition at one time of the first reagent constitutes a simplified operating mode, with relation to a dropwise addition.

According to a characteristic of the invention, when tetramethylethylenediamine is used as a diamine, they are made reacting said reagents in the presence of a quantity of diamine which can vary from 0.5 to 1 equivalent lithium, and that is advantageously substantially equal to 1 equivalent lithium, and a temperature that can vary from -20ºC to 50ºC.

It will be noted that the use of Tetramethylethylenediamine constitutes a preferred mode of embodiment of the invention.

According to another feature of the invention, when tetraethylethylenediamine is used as a diamine, it they react said reagents in the presence of a quantity of diamine which is substantially equal to 1 equivalent lithium, and to a temperature that varies from -20ºC to 50ºC.

A dilute initiator according to the invention is gets by launching the aforementioned operations. This initiator comprises a bi-adduct that results from the addition of a secondary butyl lithium molecule on each of the two double bonds carried by dialkenyl benzene, and it is such comprising said bi-adduct according to a fraction mass equal to or greater than 75% and preferably equal to or greater than 90%

Indeed, oligomeric species (oligomers of the dialkyl benzene) are advantageously present in the initiator according to a total mass fraction that is less than or equal to 25% and, preferably, less than or equal to 10%, and the residues of said reagents are advantageously present in said initiator according to a mass fraction of less than 2% and, preferably, less than 1%, which gives the initiator according to the invention a degree of purity elevated in bi-adduct.

A method according to the invention for the preparation by anionic polymerization of a diene elastomer living that has a carbon-lithium group in each one of its chain extremities, consistent said procedure in reacting in an aliphatic hydrocarbon solvent or alicyclic, at least one diene monomer conjugated to an initiator diluted, is such that it is used as an initiator diluted an initiator obtained by the procedure of the invention, so that the lithium groups of said initiator are Equalreactive at the time of polymerization.

By diene elastomer is understood, in a way known, an elastomer that has at least in part (for example, a homopolymer or a copolymer) diene monomers (carrier monomers of two carbon-carbon double bonds, conjugates or no).

Preferably, the diene elastomer prepared according to the method of the invention it belongs to a category of "essentially unsaturated" diene elastomers, that is, that they have at least a part of conjugated dienes monomers, with a rate of remains or units of dienic origin (conjugated dienes) that is greater than 15% (mol%).

Such dienic elastomer "essentially unsaturated "can be formed by any homopolymer obtained by polymerization of a conjugated diene monomer having from 4 to 12 carbon atoms, or from any copolymer obtained by copolymerization of one or several conjugated dienes with each other or with one or more aromatic vinyl compounds having at least 8 to 20 carbon atoms

Even more preferably, the elastomer dienic prepared according to the invention belongs to the category of "strongly unsaturated" diene elastomers, that is, with a rate of remains of dienic origin (conjugated dienes) which is greater than 50%

By way of conjugated dienes they agree particularly butadiene-1,3, the 2-methyl-1,3-butadiene, 2,3-di (C1-C alkyl) C 5) - 1,3, butadienes such as 2,3-dimethyl-1,3-butadiene, he 2,3-diethyl-1,3-butadiene, he 2-methyl-3-ethyl-1,3-butadiene, he 2-methyl-3-isopropyl-1,3-butadiene, an aryl-1,3-butadiene, the 1,3-pentadiene, the 2,4-hexadiene.

As compounds Vinyl aromatics are suitable, for example, styrene, ortho-, meta-, paramethylstyrene, commercial mixture "vinyltoluene", paraterciobutylstyrene, methoxystyrenes, chlorostyrenes, vinylmesitylene, divinylbenzene, vinyl naphthalene.

Particularly preferably, the dienic elastomer according to the invention is chosen from the group of highly unsaturated diene elastomers formed by polybutadienes (BR), polyisoprenes (IR) or natural rubber (NR), butadiene-styrene copolymers (SBR), butadiene-isoprene copolymers (BIR), the isoprene-styrene copolymers (SIR), the copolymers of butadiene-styrene-isoprene (SBIR) or a mixture of two or more of these compounds.

By way of polymerization solvent aliphatic, for example, cyclohexane or even methylcyclohexane.

The polymerization reaction can be carried out. in the presence or absence of an ether type polar agent, for example the tetrahydrofuran, or of the amine type, for example the tetramethylethylenediamine.

This reaction can also be carried out in presence of randomizing agents, such as sodium alcoholates.

As for the polymerization temperature, this can generally vary from 0 ° C to 90 ° C and preferably from 20 ° C to 70 ° C.

If the diene elastomer to be prepared is a polybutadiene, the process according to the invention is such that It consists of providing each of the chain ends of the polybutadiene of a butadienillitio group.

It will be noted that diene elastomers living conditions obtained by this process of the invention can run later through a group lithium carbon comprising at each end of chain, to get to obtain polymers effectively dysfunctional

It will also be noted that these polymers living so obtained can be used for polymerization subsequent, for example, a sequenced polymerization or a graft reaction, to obtain copolymers triblocks whose central block is formed by said elastomer dienic and whose terminal blocks are identical.

By way of example, in the case of a polymer living formed by polybutadiene can be prepared in this way, for example, a styrene / butadiene / styrene copolymer (SBS) by graft with a polymer formed by polystyrene. And in the case of a living polymer formed by polyisoprene, can be prepared, by example, in this way a styrene / isoprene / styrene copolymer (SIS) by an analogous graft.

The aforementioned characteristics of the present invention, as well as others, will be better understood after reading the description and the various embodiments of the invention.

1) Examples of preparation of initiators according to invention

In the following examples it has been used, to title of first and second reagents, respectively the 1,3-diisopropenylbenzene (hereinafter abbreviated m-DIB) and the secondary butyllithium (abbreviated sBuLi).

These reagents are reacted under inert atmosphere, in encapsulated bottle or in 10-liter reactor equipped with mechanical agitation means.

The diamines used, the tetramethylethylenediamine (TMED) and tetraethylethylenediamine (TEED) are distilled before use.

All obtained primers were preserved at low temperature (around -20ºC). Under these conditions, they can Store several months without losing activity.

Example one

Preparation of an initiator A by reaction between the m-DIB and sBuli at -20 ° C, in the presence of 1 equivalent tetramethylethylenediamine lithium (TMED)

In an encapsulated bottle containing 20 ml of airless heptane, 14.3 ml of a solution 1,425 mol / l is introduced of sBuLi in cyclohexane. The reaction medium is brought to -50 ° C. TO this temperature is introduced 1.7 ml of m-DIB. He medium is kept under magnetic stirring for 10 minutes, then 3 ml of tetramethylethylenediamine are introduced. The beginning of the reaction by adding diamine is translated by an increase in temperature at -20 ° C. The reactive medium is then maintained. for 5 hours at this temperature.

The title of the solution is measured by Gilman dosage. (Article J. Am. Chem. Soc. 66, 1515, 1944). Be obtains a title of 0.52 mol / 1, which corresponds to the title wanted.

Example 2

Preparation of an initiator B by reaction between the m-DIB and sBuLi at -20 ° C, in the presence of 0.5 equivalent tetramethylethylenediamine lithium (TMED)

In an encapsulated bottle containing 45 ml of airless heptane, 28.3 ml of a 1,415 mol / l solution is introduced of sBuLi in cyclohexane. The reaction medium is brought to -50 ° C. TO this temperature is introduced 3.4 ml of m-DIB. He medium is kept under magnetic stirring for 10 minutes, then 3 ml of tetramethylethylenediamine are introduced. The beginning of the reaction by adding the diamine is translated by a rise in the temperature at -20 ° C. The reactive medium is then maintained. for 1 hour at this temperature.

The reactive medium is then allowed to stand. for 12 hours in the freezer, at a temperature close to -20 ° C.

The title of the solution is measured by Gilman dosage (article J. Am. Chem. Soc. 66, 1515, 1944). Be obtains a title of 0.5 mol / 1, which corresponds to the title wanted.

Example 3

Preparation of an initiator C by reaction between the m-DIB and sBuLi at 50 ° C, in the presence of 1 equivalent tetramethylethylenediamine lithium (TMED)

In an encapsulated bottle containing 21 ml of airless heptane, 14.3 ml of a solution 1,425 mol / l is introduced of sBuLi in cyclohexane. The reaction medium is brought to 20 ° C. TO this temperature is introduced 1.7 ml of m-DIB. He medium is kept under magnetic stirring for 10 minutes, then 3 ml of tetramethylethylenediamine are introduced. The beginning of the reaction by adding the diamine is translated by a rise in the temperature at 50 ° C. The reactive medium is then maintained. for 5 hours at this temperature.

The title of the solution is measured by Gilman dosage. (Article J. Am. Chem. Soc. 66, 1515, 1944). Be obtains a title of 0.53 mol / 1, which corresponds to the title wanted.

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Example 4

Preparation of an initiator D by reaction between the m-DIB and sBuLi at 50 ° C, in the presence of 0.5 equivalent tetramethylethylenediamine lithium (TMED)

The synthesis is carried out in a 101 1 reactor provided with mechanical agitation.

In the reactor containing 4.31 heptane without air, 2.7 1 of a 1.38 mol / l solution of sBuLi is introduced into the cyclohexane, then 318 ml of m-DIB. Temperature of the reaction medium is measured at 28 ° C, the medium is kept under stirring for 15 minutes, then 284 ml of tetramethylethylenediamine. The introduction of diamine is translated by an increase in temperature, and the reactive medium reaches quickly 50 ° C. This temperature is maintained for 5 hours of reaction.

The title of the solution is measured by Gilman dosage. (Article J. Am. Chem. Soc. 66, 1515, 1944). Be obtains a title of 0.47 mol / 1, for 0.49 mol / l sought.

Example 5

Preparation of an initiator E by reaction between the m-DIB and the sBuLi at room temperature, in presence of 0.5 equivalent lithium tetramethylethylenediamine (TMED)

In an encapsulated bottle containing 20 ml of airless heptane, 14.3 ml of a solution 1,425 mol / l is introduced in cyclohexane, then 1.7 ml of m-DIB. The reaction medium temperature is measured at 23 ° C, the medium is kept under stirring for 10 minutes, then they are introduced 1.5 ml of tetramethylethylenediamine. The introduction of diamine is translates by a brutal increase in temperature to 54 ° C, to return to progressively lower and stabilize after one hour to approximately 26 ° C. In total, the medium of reaction for 5 hours of reaction.

The title of the solution is measured by Gilman dosage. (Article J. Am. Chem. Soc. 66, 1515, 1944). Be obtains a title of 0.53 mol / 1, for 0.54 mol / l sought.

Example 6

Preparation of an initiator E by reaction between the m-DIB and the sBuLi at room temperature, in presence of 0.5 equivalent lithium tetraethylethylenediamine (TEED)

In an encapsulated bottle containing 21 ml of airless heptane, 14.3 ml of a solution 1,425 mol / l is introduced of sBuLi in cyclohexane. The reaction medium is brought to -50 ° C. TO this temperature is introduced 1.7 ml of m-DIB. He medium is kept under magnetic stirring for 10 minutes, then 4.2 ml of tetramethylethylenediamine are introduced. The beginning of the reaction with the addition of diamine is translated by a temperature rise to -20ºC. The reactive medium is maintained for an hour at this temperature.

The reaction medium is then left in stand for 12 hours in the freezer at a temperature close to -20 ° C.

The title of the solution is measured by Gilman dosage (article J. Am. Chem. Soc. 66, 1515, 1944). Be obtains a title of 0.5 mol / 1, for 0.49 mol / l sought.

2 / Characterization of dilute initiators as well prepared a) Search for residual sBuli

The evidence of residual sBuLi is effect after derivatization with the 4,4-benzophenone (hereinafter abbreviated Ph2CO). The adduct SBuLi / Ph_ {2} CO is sought.

The derivatization reaction is started as follows.

A sample of reactive medium to characterize (which includes the bi-adduct. M-DIB / 2sBuLi) is diluted to 1 / 10º (volume / volume) in airless toluene, then reacts 1 hour at 60 ° C with 1.5 Lithium equivalent of Ph2CO. The medium is protonated next by adding a large excess of methanol.

The reaction mixture is then characterized by gas phase chromatography.

The device used is a chromatograph marketed by HeWLETT PACKARD under the name "5890."

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b) Search for residual m-DIB

A sample of this reagent medium is protonated by adding a large excess of methanol, then analyzed by gas phase chromatography.

The apparatus used is a chromatograph marketed by HeWLETT PACKARD under the designation
"5890."

c) Evidence of quantity training majority of the bi-adduct (DIB / 2 sBuLi)

A sample of the reactive medium is protonated by addition of a large excess of methanol is then analyzed by gas phase chromatography coupled to mass spectrometry (CPG / SM) using electronic impact as an ionization mode (IE), as well as by direct introduction of the sample into the source of a mass spectrometer, using the two ionization modes electronic impact and (IE) and chemical ionization (IC) by gas ammonia, so that the spaces are evident oligomers formed by polymerization of the m-DIB.

The device used for CPG / SM analysis is a chromatograph marketed by HEWLETT PACKARD under the designation "MSD 5973"; direct introduction analyzes they are made on a mass spectrometer marketed by NERMAG under the designation `` R10 10-C).

These analyzes have shown that the compound formed in majority quantity is the bi-adduct. DIB / 2 sBuLi, of molecular mass equal to 274 g / mol.

d) Quantification of oligomeric species

The initiator is characterized by the technique of size exclusion chromatography (called technique "SEC").

The initiator is prepared to analyze in the way next.

A sample of the aforementioned reagent medium is diluted to 1 / 5th (volume / volume) in toluene without air, then proton by adding a large excess of methanol.

The sample is then washed with water until neutral, then the solvent is removed by entrainment of the
nitrogen.

The initiator sample to be analyzed is solubilized in tetrahydrofuran, at a concentration of approximately
1 g / l

The device used is a WATERS chromatograph of model "150C". the elution solvent is the tetrahydrofuran, flow rate of 1 ml / min., system temperature of 35ºC and the duration of analysis of 40 min. The injected volume of The sample of initiator is 100 µl. The detector is a WATERS differential refractometer of model "R401" and the logical Acquisition and processing of chromatographic data is the logical MILLENIUM marketed by WATERS (version 2.10).

The contrast of the measuring device is performed from polystyrene patterns.

The percentage of oligomers formed is calculated by making the ratio of the surface area of the peaks corresponding to the different oligomeric species over the total surface area located under the molecular mass distribution curve. The surfaces are provided by the logical exploitation of chromato data.
graphics.

e) Results obtained

The following table shows the set of results obtained for the characterization of said initiators A to F.

For each of the initiators the rates of Buli and residual m-DIBs are expressed in percentages of the corresponding amounts that have been introduced by the reaction. As for species rates oligomeric with m-DIB, are expressed in percentages Mass.

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Initiator SBuLi residual DIB residual Oligomeric species (SEC analysis) TO 0.95% 0.22% \ sim7% B 1.4% <0.04% \ sim10% C 0.08% <0.02% \ sim5% D 0.13% <0.02% \ sim18% AND 1.1% 0.16% \ sim13% F <0.014% <0.02% \ sim25%

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By way of illustration they are represented in the Figures 1 and 2 the molecular mass distribution curves for initiators B and F whose synthesis is described respectively in examples 2 and 6 of section 1 /.

The cited results table and these graphs show that the reaction between m-DIB and sBuLi is effectively oriented towards the formation of bi-adduct (m-DIB / 2 sBuLi). In In effect, the residual sBuLi and m-DIB rates are very weak (less than 1% of the amount introduced) and the formation of oligomers of m-DIB it is limited to a mass fraction that ranges from 5% to 25% according to the examples.

Consequently, diluted initiators obtained by a process according to the invention are such that they are almost exclusively formed by said bi-adduct

3 / Comparative examples of preparation of initiators not according to the invention and its characterization

Example 7

Preparation of an initiator G by reaction between the m-DIB and linear butyllithium (n-BuLi) at -20 ° C, in the presence of 1 equivalent tetramethylethylenediamine lithium (TMED)

This example is characterized by the same preparation conditions than in example 1 of section 1 /, except that the secondary butyllithium is replaced by butyllithium linear.

In an encapsulated bottle containing 20 ml of airless heptane, 7.85 ml of a 2.6 mol / l solution of sBuLi in cyclohexane. The reaction medium is brought to -50 ° C. TO this temperature is introduced 1.7 ml of m-DIB. He medium is kept under magnetic stirring for 10 minutes, then 3 ml of TMED are introduced. The beginning of the reaction to adding diamine results in an increase in temperature to -20 ° C. The reactive medium is then maintained for 5 hours. at this temperature

A heterogeneous medium is obtained with the presence of a precipitate

The analysis by exclusion chromatography by The size (SEC) reveals the presence of insoluble species. The bi-adduct ratio is evaluated at less than 5% in mass.

Consequently, this example shows that the single substitution of the secondary butyllithium by its linear counterpart, in the preparation procedure of an initiator according to the invention guides the reaction between the m-DIB and the n-BuLi towards the formation of oligomeric species which are insoluble in the reactive medium. The reactivity of n-BuLi is insufficient to lead to training of the bi-adduct, by addition on the facilities of the m-DIB molecule.

Example 8

Preparation of an initiator H by reaction between the m-DIB and the secondary butyllithium (s-BuLi) at -20 ° C, in the presence of 1 equivalent triethylamine lithium (TMED)

This example is characterized by the same preparation conditions than in example 1 of section 1 /, except that tetramethylethylenediamine (TMED) is replaced by triethylamine, which has been distilled before use.

In an encapsulated bottle containing 20 ml of airless heptane, 14.3 ml of a solution 1,425 mol / l is introduced of sBuLi in cyclohexane. The reaction medium is brought to -50 ° C. TO this temperature is introduced 1.7 ml of m-DIB. He medium is kept under magnetic stirring for 10 minutes, then 3 ml of tetramethylethylenediamine are introduced. The beginning of the reaction by adding the diamine is translated by a rise in the temperature at -20 ° C. The reactive medium is then maintained. for 5 hours at this temperature.

The analysis by exclusion chromatography by The size (SEC) reveals the presence of oligomers in quantities important (of the order of 5 0% by mass).

Consequently, this example shows that the single substitution of TMED with thiethylamine in the procedure of preparing an initiator according to the invention, orients the reaction between m-DIB and n-BuLi towards the formation of oligomers in significant quantities, which considerably reduces the purity of bi-adduct

4 / Examples of preparation of living polybutadienes by means of initiators according to the invention

Low mass polybutadienes are prepared molecular (50 000 g / mol) comprising a bond butadienyl lithium in each of the two extremities of the polymer chain.

The following examples refer respectively to the use of initiators A to F that have been prepared according to examples 1 to 6 of section 1 /.

The reactions of polymerization under inert atmosphere, in encapsulated bottle, and performing the following experimental protocol each time.

In 45 ml of deciclohexane without air, introduce 5 g of butadiene. After compensation of impurities contributed by the solvent and the monomer with the help of n-butyllithium, an initiator volume is introduced diluted corresponding to 200 µmoles of links lithium carbon The polymerization is carried out at 60 ° C. After the total conversion of the monomer, 1.2 ml of a 0.25 mol / l solution of chlorotrimethylsilane (Si / Li ratio = 1.5) in cyclohexane. After 30 minutes, the polymer will proton by adding 2 ml of 2 mol / l methanol solution in the Toluene. The polymer is antioxidated by the addition of 2,2'-methylene bis-4 methyl-6 third-butylphenol (1 g for 100 g of monomer). The elastomer is then dried at 50 ° C under pressure reduced

5 / Characterization of the polybutadienes obtained a) Distribution of molecular masses (DDM)

A characterization of the polymers obtained by the exclusion chromatography technique by the size (SEC technique). This consists of physically separating the macromolecules according to their size in swollen state, on columns full of a stationary phase. The macromolecules are separated by its hydrodynamic volume, choosing first the most bulky

Without being an absolute method, the SEC technique, which use a differential refractometer, it is a tool adapted to apprehend the molecular mass distribution of a polymer. From contrast products whose characteristics are described in the European patent document EP-A-692 493, the Mean molecular masses in number (Mn) and in weight (Mw) as described in said document, and the index of polydispersity (Ip = Mw / Mn).

The sample to be analyzed is previously solubilized in tetrahydrofuran at a concentration of about 1 g / l

The device used is a chromatograph "WATERS" of model "150C". the elution solvent is the tetrahydrofuran, flow rate of 1 ml / min., system temperature 35 ° C and the analysis duration of 30 min.

The injected volume of the initiator sample Diluted is 100 µl.

The detector is a differential refractometer "WATERS" of model "R401" and the logical exploitation of Chromatographic data is the system marketed under the denomination "WATERS MILLENUM" (version 2.10).

b) Molecular mass in number (Mn) determined by osmometry

The device used is a membrane osmometer "GONOTEC" semipermeable model "Osmomat 090". He polymer to be analyzed is put in solution in toluene, at a concentration of approximately 10 g / l. The measurement is made at 50 ° C

c) Evidence of the activity of each of the two C-li sites that carry the initiator molecule at the time of polymerization of butadiene

For each of these initiators A to F, it has been evidenced with 1 H NMR the absence of lithiated site not active during the polymerization of butadiene, after functionalization of the extremities of the chain with the chlorotrimethylsilane (CISiMe3) which is a reagent known for react with the carbon-lithium groups.

Indeed, if only one limb has been initiated string, there are finally two functions of a different nature on both ends of the polymer chain:

a first function butadienyl-Li and a corresponding second function to the lithiated site of the initiator (m-DIB-Li).

The evidence of the activity of C-li sites rests on the fact that, after the reaction with ClSiMe 3 the protons of the methyl groups resonate at different frequencies, depending on your type environment butadienyl or m-DIB type.

The polymer sample to be analyzed is prepared from The following way.

The polymer obtained is coagulated in methanol after the reaction with ClSiMe 3, protonated in methanol and antioxidant by the addition of 2,2'-methylene bis-4, methyl-6 third-butylphenol, then it is put back twice in solution in toluene and in methanol for coagulation. The polymer is then dried to 50 ° C under reduced pressure and nitrogen sweep.

1 H NMR analysis of the polymer is carried out as follows:

A sample is solubilized in carbon sulphide of the polymer so treated. It is used for signal analysis 1 H NMR a spectrometer marketed under the designation "BRUKER AC200".

The three metallic protons of the rest

\melm{\delm{\para}{CH _{2} -sBu}}{C}{\uelm{\para}{CH _{3} }}

--- Si --- CH_{3})m --- DIB --- Si (C H 3) (--- Ph ---

 \ melm {\ delm {\ para} {CH 2 -sBu}} {C} {\ uelm {\ para} {CH 3}} 

--- Yes --- C H 3)

are characterized by a massif towards -0.2 ppm. The three metallic protons of the rest butadienyl-Si (CH 3) are characterized by a massif between 0 and -0.1 ppm.

d) Results obtained

The following table takes into account the set of results obtained for the characterization of polybutadienes respectively prepared by means of said initiators A to F.

For each of the polybutadienes obtained, indicate the average molecular masses in number Mn (g / mol) and the Ip polydispersity index (both determined by the technique SEC), the average molecular mass in number Mn_ {osmo} (measured by osmometry), as well as the mass rate of vinyl chains (determined by 1 H NMR, in%).

Polybutadienes Initiator Mn Ip Mnosmo Rate from (g / mol) (g / mol) chains (SEC technique) (osmometry) vinyl (%) one TO 42208 1.07 50,000 68 2 B 43118 1.07 50,000 53 3 C 42405 1.1 50,000 68 4 D 43256 1.09 50,000 53 5 AND 43897 1.06 52000 52 6 F 45262 1.08 55000 44

For each of the polybutadienes 1 to 6 have pointed out the remains functionalized-Si (Me) 3 between 0 and 0.1 ppm, which corresponds to the protons of the rest butadienyl-Si (CH 3). Not detected No signal in the area of -0.2 ppm.

For each of these polybutadienes 1 to 6, the respective integrations of aromatic protons (solid centered on 7 ppm) and the signal corresponding to the rest -If (CH 3) 2 (mass between 0 and -0.1 ppm) are well within the expected proportion.

By way of illustration, then the molecular mass distribution curve for polybutadiene 3 synthesized from initiator C.

In conclusion, it will be noted that each of the synthesized polymers have a molecular mass in number Mn_ {osmo} measured by osmometry that agrees with the value theoretical. In addition the distribution of molecular masses is single mode and narrow (Ip <1,1).

It will also be noted that the two sites present on the bi-adduct m-DIB / 2 sBuLi are equally active in polymerization. In effect, the 1 H NMR analysis of each of the polymers after functionalization of the chain extremities, by reaction with the chlorotrimethylsilane, has shown that these sites are transformed into Butadienyl-Li.

In summary, each of the initiators A to F according to the invention behaves as an initiator effectively dysfunctional, in the sense of the equirreactivity of the sites lithium carbon carried by the molecule.

6 / Examples of preparation of triblock copolymers styrene / butadiene / styrene

Initiator D, whose synthesis conditions are described in example 4 of section 1 / above, has been used for the synthesis of a triblock copolymer styrene / butadiene / styrene (SBS) that has a polystyrene block in each of the chain extremities.

By way of comparison, it has been synthesized also the butadiene / styrene diblock copolymer thereof molecular mass using n-butyllithium for initiation.

The reactions of polymerization under an inert atmosphere, in a 10 liter reactor equipped with mechanical agitation.

a) Synthesis of the triblock copolymer

In 4 liters of cyclohexane without air, introduce 201 g of butadiene. After compensation of impurities contributed by the solvent and the monomer with the help of n-butyllithium, an initiator volume is introduced corresponding to 4 mmol of lithium carbon bonds. Polymerization of the polybutadiene block is carried out at 60 ° C. After the conversion of the entire butadiene are introduced 99 g of styrene which polymerizes at 60 ° C for 80 minutes. He copolymer is then protonated with the addition of a broad excess methanol in solution in toluene, it is antioxidized by addition of 2,2'-methylene-bis-4methyl-6 tertbutylphenol (1 g for 100 g of monomer), then recover by steam separation and dried in an oven under pressure reduced to 60 ° C.

The polymer obtained has the following features:

MN (g / mol) determined by osmometry: 150,000 g / mol Index of polydispersity 1.12 Cup of vinyl chains (% mass) 40 Rate of built-in styrene (% mass) 32

b) Synthesis of the diblock copolymer

In 4 liters of cyclohexane without air, introduce 186 g of butadiene and 2.4 ml of a 0.5 M solution of tetramethylethylenediamine in cyclohexane. After the compensation of impurities contributed by the solvent and the monomer with the help of n-butyllithium, 3.7 is introduced ml of a 0.5 mol / l n-butyllithium solution in cyclohexane Polymerization of the polybutadiene block is effect at 60 ° C. After the conversion of the entire Butadiene introduces 114 g of styrene which polymerizes at 60 ° C for 60 minutes The copolymer is then protonated with the adding a large excess of methanol in solution in toluene, it antioxidant by adding 2,2'-methylene-bis-4methyl-6 tertbutylphenol (1 g for 100 g of monomer), then recovered by steam separation and dried in an oven under pressure reduced to 60 ° C. The polymer obtained has the following features:

MN (g / mol) determined by osmometry: 145,000 g / mol Index of polydispersity 1.08 Cup of vinyl chains (% mass) 39 Rate of built-in styrene (% mass) 33

7 / Mechanical characterization of these copolymers styrene / butadiene / styrene block

The following table takes into account the stress / elongation properties of SBS copolymers of uncrosslinked blocks whose synthesis is described in section 6 /. For each of these copolymers, the apparent stress is indicated. of breakage (MPa), the deformation at break (in%), as well as the secant modules MS at 10%, 50%, 100% and 300% deformation (MPa).

The measurements have been made on a INSTRON 4501 machine at 23ºC at a traction speed of 1 m / min., on specimens of the "haltère" type taken from polymer plates 2.5 mm thick, molded for 10 min at 110 ° C, and then cooled under press for 20 hours.

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Triblock Diblock Breakage stress (MPa) 8.29 0.68 Breakage deformation (%) 745.4 52.5 MS 10% 19.31 1.63 MS fifty% 4,5 1.32 MS 100% 2.13 0.54 MS 300% 0.953 0.001

The copolymer obtained from the initiator according to the present invention it has clearly higher modules than those of the copolymer initiated to n-butyllithium. The levels of stress and elongation of breakage are equally very superior.

In conclusion, it is important to insist on the triblock structure of the copolymer formed from the initiator according to the invention, what proves, as mentioned in the examples above, the perfectly dysfunctional character I said initiator in the sense of the e-reactivity of the sites lithium carbon that carries the molecule.

Claims (10)

1. Procedure for preparing a dilute initiator usable in anionic polymerization, consisting of reacting in a solvent aliphatic or alicyclic hydrocarbonate a first reagent consisting of a dialkenylbenzene and a second reagent consisting of secondary butyllithium, such that the reaction of the number of moles of the first reagent to the number of moles of the second reagent is substantially equal to 0.5, characterized in that it consists in reacting said reagents in the presence of a diamine, so that the obtained initiator is essentially constituted by a bi-adduct resulting from the Addition of a secondary butyllithium molecule on each of the double bonds carried by said dialkenylbenzene. 2. Process for preparing a dilute initiator according to claim 1, characterized in that said diamine is introduced into a reaction mixture comprising said reagents. 3. Method of preparing a dilute initiator according to claims 1 or 2, characterized in that it consists of adding at once said first reagent to said second reagent. 4. Method of preparing a dilute initiator according to claims 1 to 3, characterized in that it consists in reacting said reagents in the presence of a quantity of diamine ranging from 0.5 to 1 equivalent lithium. 5. Method of preparing a dilute initiator according to claim 4, characterized in that it consists in reacting said reagents in the presence of a quantity of diamine that is substantially equal to 1 equivalent lithium. Method for preparing a dilute initiator according to claims 1 to 5, characterized in that it consists in using, as a diamine, a diamine belonging to the group consisting of tetramethylethylenediamine and tetraethylethylenediamine. 7. Method of preparing a dilute initiator according to claim 6, characterized in that it consists in reacting said reagents in the presence of tetramethylethylenediamine. 8. Method of preparing a dilute initiator according to claim 7, characterized in that said reactants are reacted in the presence of tetramethylethylenediamine at a temperature ranging from -20 ° C to 50 ° C. 9. Method of preparing a dilute initiator according to claim 6, characterized in that it consists in reacting said reagents in the presence of tetraethylethylenediamine. 10. Process for preparing a dilute initiator according to claims 5 and 9, characterized in that it consists in reacting said reagents in the presence of tetraethylethylenediamine at a temperature ranging from -20 ° C to 50 ° C.